1. Field of the Invention
The present invention relates to a multi-fluidized bed water-gas shift reactor using a synthesis gas (“syngas”) and a method for production of hydrogen using the same and, more particularly, to a multi-fluidized bed water-gas shift reactor wherein a specific syngas containing a high concentration of carbon monoxide produced by gasification of a heavy carbon source such as coal, vacuum residue, glycerin, etc., is in contact with water under a catalyst so as to produce hydrogen and, in addition, a method for production of hydrogen using the foregoing reactor. Briefly, the present invention discloses a multi-fluidized bed water-gas shift reactor containing low and high temperature catalysts as well as water vapor (or steam) and a method for production of hydrogen using the same, wherein 30 to 70% carbon monoxide in a syngas as a gas mixture containing hydrogen, carbon monoxide, carbon dioxide, hydrogen sulfide, hydrogen monoxide, and the like, which are generated through partial oxidation and vapor gasification at 900 to 1,600° C., may be favorably converted into hydrogen without mixing both of the catalysts.
2. Description of the Related Art
Since energy conversion through combustion of fossil fuels such as coal, petroleum oil, natural gas, etc., causes serious environmental problems including global warming, practical applications of clean energy conversion technologies other than fossil fuel combustion are increasingly being conducted.
Especially, as a technique for production of hydrogen recognized as a high value future energy resource at economically feasible costs while removing carbon dioxide causing global warming has beneficial features, a number of gasification processes using a fractional bed, a fluidized bed, a fixed bed and the like have been developed in order to achieve the foregoing hydrogen production.
The gasification process using various hydrocarbon materials generates hydrogen as a representative clean fuel; however, an amount of the produced hydrogen is only within 10 to 40% depending on fuel sources, gasification agents, reactor types, operational conditions, etc. Accordingly, a syngas generated during general gasification usually contains a larger amount of carbon monoxide than hydrogen.
Therefore, for practical applications of advanced technologies such as a fuel cell vehicle, a hydrogen engine, a high efficiency hydrogen-combined power generation, and so forth, it is necessary to convert a large amount of carbon monoxide contained in the syngas into hydrogen. Moreover, economical separation of carbon dioxide as an advantage of the gasification process also requires conversion of carbon monoxide in the syngas into hydrogen, thereby ultimately producing a high concentration hydrogen containing flow consisting of hydrogen and carbon dioxide only.
In order to convert carbon monoxide into hydrogen, a conventional fixed bed water-gas shift reactor used for a natural gas reforming process is usually employed. However, such fixed bed water-gas shift reactor has difficulty in operation under conditions of a syngas for gasification that contains 30 to 70% carbon monoxide relative to a total amount of the syngas.
The reason for this is that, as disclosed in published patents, e.g., in Korean Patent No. 0462286 which describes a water-gas conversion catalyst comprising ceramics supported on a metal and a preparation method thereof, recent developments related to water-gas shift reaction have mostly focused on a catalyst rather than improvement of a water-gas shift reactor.
Alternatively, an incineration method using thermal energy to generate the water-gas was disclosed in Korean Patent No. 0834298. This is adapted as a pre-process for combustion instead of generating hydrogen, thus having low hydrogen conversion.
For a waste gasification described in recent patent applications, 30 to 50% carbon monoxide generated during gasification is subjected to treatment and, at the same time, an existing fixed bed/fluidized bed mode is practically embodied. In this regard, a double-layered configuration of the bed may be adopted. However, catalyst loss caused by a bubble fluidized bed process is not continuously supplemented and temperature control is executed only by vapor injection. Therefore, efficiency of carbon monoxide treatment may be relatively low.
Under the foregoing circumstances, in order to increase production of hydrogen used as an energy source, there is still a requirement for development of a process and an apparatus capable of converting 30 to 70% carbon monoxide in a gas mixture into hydrogen, which in turn may favorably enhance hydrogen production.